Switching on and off a well-controlled coupling between circuit parts is essential in quantum technology. We propose a novel tunable coupling scheme consisting of N fixed-frequency qubits. We show that the interaction between two general quantum circuits can be tuned by inserting an ensemble of qubits as a mediator and engineering them in different dark states. Most interestingly, we find that a large qubit ensemble can make the effective interaction even larger than the physical interaction between two adjacent circuit components.

Quantum Teleportation

An international team headed by physicists from the Walther-Meißner-Institute (WMI) and Technical University of Munich (TUM) has, for the first time ever, experimentally implemented quantum teleportation based on propagating microwave signals between distant locations while preserving the fragile quantum nature of teleported states. This key achievement opens the avenue towards distributed quantum computing in networks of superconducting quantum computers. The work has been performed in collaboration with Japanese scientists from the RIKEN Center for Quantum Computing.

Sci. Adv. 7, eabk0891 (2021)
DOI: 10.1126/sciadv.abk0891

Characterization and Tomography of a Hidden Qubit

In state-of-the-art quantum computing systems, each quantum bit can be individually controlled and measured. Large systems of qubits thus require a large amount of control electronics and signal lines, which are costly resources. One way to increase the number of qubits without also multiplying auxiliary resources is simply to add “hidden” qubits that are not directly controlled or read out. These are operated indirectly, using interactions with their neighboring qubits and do not require a separate control line. In our experiment, we demonstrate full control over a superconducting two-qubit system even though only one of the qubits is directly addressable.

Science outreach

Within the Marie Curie european network QuSCo, our students Federico Roy and Max Werninghaus collaborated with colleagues from various fields to apply optimal control to quantum systems. Over the course of the three-year program, the ESRs were trained in science education and outreach. Check out the playlist on youtube to learn more about how we approach science education!

1 open PhD position (m/f/d)

on the experimental realization of a superconducting microwave single-photon detector

WMI Supports the Scientific Program of "FORSCHA"

Discover what moves the world! This was the motto of the Münchener Wissenschaftstage 2021, taking place at the Deutsches Museum Verkehrszentrum from October 08 to 10. Rudolf Gross of WMI supported the scientific program of the event by a public talk on quantum computing and the Excellence Cluster MCQST was informing the public on its research activities at a booth. 

The Münchener Wissenschaftstage offered an adventure trip throught the fascinating world of science and technology. The visitors could get first-hand information on newest developments in science, technology, economy, world of work, education, art and culture. Quantum science and technology was one of the topics attracting the biggest audience, demonstrating the large interest of the public in hightech.


3 open PhD positions (m/f/d)

targeted with the experimental realization of microwave quantum token with quantum memory based on spin ensembles

Munich Quantum Valley receives funding by the Bava

The Bavarian State Ministry of Science and Arts annouced funding of 80 Mio. euros for the Munich Quantum Valley (MQV) for 2021-2026. The ambitious goal is to develop the hard- and software for quantum computers. The WMI takes a leading role in the ambitious journey towards the realization of superconducting quantum computers.

"Bavaria aims to take the lead in quantum research and the application of quantum technologies in Germany and Europe", State Minister Bernd Sibler says. By establishing the Munich Quantum Valley, Bavaria will bundle its already outstanding scientific competences in the Munich area and establish a powerful ecosystem joining researchers, engineers, industrial leaders and venture capitalists. This goal will be supported by a matching funding program of the State Ministry of Economics. "Important future technologies and apllications should come from Bavaria. Therefore, the funding for MQV represents an important investment into Bavaria as a leading high-tech region", State Ministery Hubert Aiwanger points out.

WMI bids farewell to Prof. B.S. Chandrasekhar

WMI mourns for Prof. B.S. Chandrasekhar who died on 12th September 2021 at the age of 93. He had been guest professor at WMI since 1988 and contributed to the success of many research projects by his creativity and deep knowledge of physics. We will honor his memory and remember him not only as a great scientist but also as a charming and humorous colleague.

B.S. Chandrasekhar studied physics at the Universities of Mysore and Delhi and received his Ph.D. from the University of Oxford in 1952. He then became research associate at the University of Illinois at Urbana Champaign (1952-54) and visiting scientist at the University of Oxford  (1954-55). In 1955, he joined the Westinghouse Research Labs, where he did his well-known work on the upper critical field of type-II superconductors (Chandrasekhar-Clogston limit, 1962). In 1963, he became professor of physics at the Case Western Reserve University in Cleveland, where he has also been department chair, dean and vice president. He retired from CWRU in 1988. He also was guest professor at the University of Cambridge (1978), the Tata Institute at Bombay (1980), the ETH Zurich (1980-81) and the WMI (1984-85). After retiring from Case Western Reserve University he joined WMI as a permanent guest researcher in 1988.

Quantum Technology Outreach Event QuantTech

We are hosting a quantum technology event organized by our partners at QuSCo: get to know quantum technology researchers and their work in a casual setting. Chat with quantum researchers and learn about quantum sensing with hands-on tools. The visit will also include brief visits of our quantum computing laboratory, which hosts the latest iterations of WMI-built quantum processing chips. Join us on September 8 at our Institute in Garching, Munich. 

For more information visit the registration site:

WMI-Seminar Talk by Matthias Mergenthaler (IBM Research - Zurich) - 10:15am

Title: Effects of surface treatments and UHV packaging on flux tunable transmon qubits

Congratulations to Philipp Krüger

Philipp Krüger of WMI has been awarded a Best Poster Prize for his excellent poster contribution on "Microwave Quantum Key Distribution in a Noisy Environment" presented at the International Conference on Quantum Science & Technology organized by the Excellence Cluster MCQST.

The Best Poster Award has been handed over within the Award Ceremony Session on 23 July 2021 together with a prize money donated by Menlo Systems GmbH.

Obituary for Johneph Sukham †

On July 3, Johneph Sukham died in a tragic accident. We feel great sadness and will miss Johneph as an inspiring colleague and friend. RIP.

Welt der Quanten

There is a tremendous progress in quantum research and the development of quantum technologies, and their application potential is huge. In a focus issue of the journal "Akademie Aktuell" scientists of the Walther-Meißner-Institute explain the present research directions in quantum science and technology. They also discuss the future impact of quantum technology for all of us.

Munich is on of the internationally leading centers for quantum science and technology. This leading position has been further strengthened  by the start of the excellence cluster  Munich Center for Quantum Science and Technology (MCQST) in 2019 and the foundation of the Munich Quantum Valley (MQV) in 2021. The latter will be supported by the Bavarian state government by 300 Mio. Euro. The Walther-Meißner-Institute is one of the key players pushing the dynamic development since almost two decades.


Federico Roy, Nicolas Wittler and Max Werninghaus in a collaboration between Saarland University, IBM Research, Forschungszentrum Jülich and WMI describe how optimal control methods can be used in system characterization to achieve a "Good Model". They outline a new method for Control, Calibration and Characterization (C3) of quantum devices based on the complete understanding of the system and using optimal control. C3 provides us with the tools to achieve this goal and push us further in the quest for high-fidelity quantum devices.

Integrated Tool Set for Control, Calibration, and Characterization of Quantum Devices Applied to Superconducting Qubits
Nicolas Wittler et al., Phys. Rev. Applied 15, 034080 (2021).

Contactless high performance power transmission

A team led by physicists Christoph Utschick and Prof. Rudolf Gross has succeeded in making a coil with superconducting wires capable of transmitting power in the range of more than five kilowatts contactless and with only small losses. The wide field of conceivable applications include autonomous industrial robots, medical equipment, vehicles and even aircraft.

Superconducting Wireless Power Transfer Beyond 5 kW at High Power Density for Industrial Applications and Fast Battery Charging
Christoph Utschick et al., IEEE Trans. Appl. Supercond. 31, 5500110 (2021)

Munich Quantum Valley Kick-Off

To build a quantum computers that can solve complex scientific and economic problems faster than any supercomputer; to create infrastructures that facilitate technology transfer and the exchange of ideas in the field of quantum sciences; to offer excellent education and training opportunities for the specialists of tomorrow.

Learn more about the Munich Quantum Valley Initiative, about the status quo of quantum technologies in Bavaria and about the future opportunities that will arise for Bavaria through the development of these disruptive technologies: Thursday, 04 March 2021 from 10 am - 12 pm (CET) via livestream on Youtube.

Spin Transport and Current-Induced Torques in Superconductor-Ferromagnet Heterostructures

Researchers of WMI in a collaboration with the Norwegian University of Science and Technology at Trondheim and the University of Konstanz  successfully realized the injection of quasiparticle spin currents into a superconductor (NbN) via spin pumping from an adjacent ferromagnetic metal (Py). Using a phase sensitive detection method they can quantitatively extract the spin current-induced torques. Below Tc, they observe a suppression of the damping-like torque and a large field-like current-induced torque.

Temperature-Dependent Spin Transport and Current-Induced Torques in Superconductor-Ferromagnet Heterostructures
Manuel Müller et al., Phys. Rev. Lett. 126, 087201 (2021).

Zeeman Spin-Orbit Coupling and Magnetic Quantum Oscillations in Antiferromagnetic Conductors

Solid-state spin physics arising from spin-orbit coupling is linked to symmetry-protected degeneracies. In an international collaboration researchers of WMI proove that this is also true for Zeeman spin-orbit coupling in antiferromagnetic conductors. They show that the Néel state of the organic conductor κ-(BETS)2FeBr4 shows no spin modulation of the Shubnikov-de Haas oscillations, contrary to its paramagnetic state. A comparative study of the electron-doped high Tc superconductor Nd1.85Ce0.15CuO4  provides clear evidence for the presence of Néel order even at optimal doping.

Zeeman Spin-Orbit Coupling and Magnetic Quantum Oscillations in Antiferromagnetic Conductors
R. Ramazashvili et al., npj Quantum Mater. 6, 11 (2021).

Speeding up quantum gates

Max Werninghaus and Federico Roy at IBM Research in collaboration with Forschungszentrum Jülich and Walther-Meissner-Institute (WMI) experimentally applied optimal control methods to superconducting qubit pulses and achieve a 7-fold reduction of state leakage and a 3-fold reduction of standard errors for fast control pulses.

Leakage reduction in fast superconducting qubit gates via optimal control
Max Werninghaus et al., npj Quantum Inf. 7, 14 (2021)

Quantum Computing in Germany

Building a quantum processor with novel properties based on superconducting qubits - this is the aim of the four year project GeQCoS ('German Quantum Computer based on Superconducting Qubits') funded by the BMBF that we aim to realize at the WMI (Bavarian Academy of Sciences) in collaboration with Infineon Technologies, University of Erlangen-Nuremberg, University of Karlsruhe and Fraunhofer-Gesellschaft.

Munich Quantum Valley

The Bavarian Academy of Science and Humanities, the Fraunhofer Society, the Max Planck Society for the Advancement of Science and both Munich Universities LMU and TU Munich join forces to estalish the Munich Quantum Valley to push forward research and innovation in quantum technologies and quantum computing. 

Pseudospin in antiferromagnets

A team of researchers from the Technical University of Munich (TUM), the Bavarian Academy of Sciences and Humanities (BAdW) and the Norwegian University of Science and Technology (NTNU) in Trondheim has discovered an exciting method for controlling spin carried by quantized spin wave excitations in antiferromagnetic insulators.

Observation of Antiferromagnetic Magnon Pseudospin Dynamics and the Hanle Effect
Tobias Wimmer et al.,  Phys. Rev. Lett. 125, 247204 (2020).

The Return of the Spin Echo

A team of researchers from the Technical University of Munich (TUM), TU Wien (Vienna University of Technology) and the Bavarian Academy of Sciences and Humanities have discovered a remarkable spin echo effect – this effect presents exciting, new opportunities for working with quantum information.

Echo Trains in Pulsed Electron Spin Resonance of a Strongly Coupled Spin Ensemble
S. Weichselbaumer et al., Physical Review Letters 125, 137701 (2020)